Harun Mbuvi and Francis maingiMwaura Dominic Munyu, Dominic Munyu2024-05-312024-05-312023-11https://ir-library.ku.ac.ke/handle/123456789/28053AbstractABSTRACT Heavy metals pose serious environmental and health effects in the society since they are toxic and non-biodegradable. Removing aqueous heavy metals from solution especially wastewater has become an area of study in the recent past. Various methods like ion exchange, reverse osmosis, coagulation, and adsorption among others have been put forth in the removal of heavy metal ions. There is little information in the literature on the use of geopolymer filters in adsorption. This study focused on the removal of heavy metal ions of Pb(II), and Cu(II) from an aqueous medium using geopolymer filters fabricated from geopolymer and activated carbon. Geopolymers were used for the adsorption of the heavy metal ions, while activated was to increase porosity in the filter. Geopolymers are easily synthesized using locally available materials, are easy to use, and are environmentally friendly. Common clay was used as a source of alumina, and silica which are important ingredients of geopolymerization, and sugarcane bagasse ash was to provide extra silica. The activated carbon that was used in this study was derived from saw dust. The raw materials for the geopolymerization process and activated carbon process were sourced locally. Characterization of the geopolymer and activated carbon was done using XRF, XRD, and FT-IR.XRF identified the mineral composition of the raw materials, geopolymer, and activated carbon. FT-IR was used to find out the functional groups in both the geopolymer Al-O, Si-O, and activated carbon. XRD was used to identify that both the geopolymer and activated carbon were amorphous broad peaks between 20° 34° in 2-theta hence adsorption of heavy metal ions would occur and, carbon would have good porosity. Adsorption application of the geopolymer filter was done using an aqueous medium while varying geopolymer: activated carbon ratio where a 2:1 ratio was used, filter thickness of 4 cm was used for 50ml solution, pH the optimum range was 4-6.5 for both metal ions, and initial metal ion concentration; adsorption was above 85% for both metal ions when the concentration range was 15-150mg/L, above this concentrations, the adsorption efficiency reduced but not below 50%. The experimental data obtained were treated using Freundlich and Langmuir adsorption isotherm models to understand if the adsorption sites were homogenous or heterogeneous. Based on the correction coefficient (R2), Freudliuch isotherm was best fitted to predict the adsorption capacity of the geopolymer adsorbent for both Pb(II) metal ions, and Cu(II) metal ions with the heterogenous index being between 0-1. This illustrates that the geopolymer filter has a multilayer adsorption sites on its surface. From the adsorption data, it is clear that geopolymers and activated carbon can be used to fabricate water filters that can adsorb heavy metal ions and maintain good porosity. The filters are potential adsorbents for heavy metals from water treatment.enThesis